An organic light emitting device is a device in which a thin film containing a fluorescent or phosphorescent organic compound is sandwiched in between a pair of electrodes. An exciton of the fluorescent or phosphorescent organic compound is generated by injecting electrons and holes (positive holes) from each of the electrodes, and when the exciton returns to its ground state, the organic light emitting device emits light. Recent progress in technology of organic light emitting devices is remarkable. As characteristics of organic light emitting devices, for example, high luminance by application of low voltage, versatility of light emission wavelengths, high-speed responsibility, slimming down of a light emitting device, and weight reduction can be achieved. This suggests that organic light emitting devices have the potential for being adaptable to a wide variety of applications.
However, in light of commercial application and practical use to a full-color display and the like, it is essential for organic light emitting devices to improve their light emitting efficiency, color purity and operating life of the devices. Especially for blue-color light emitting devices, the development of a material with high color purity and high light emitting efficiency is desired; however, there are a few materials that can satisfy the requirements because of difficulties of the development.
Meanwhile, with a view to achieving high light efficiency and improving the stability of an organic light emitting device which emits blue light, a variety of materials and device configurations have been proposed. For example, PTL 1 proposes a host material having a pyrene skeleton and a light emitting dopant having a fluoranthene skeleton. Here, a material having a pyrene skeleton is excellent in electron transportability, whereas a light emitting dopant having a fluoranthene skeleton functions as an electron trap. Thus, with use of these materials, the carrier off-balance and an eccentric distribution of light emission areas can be eliminated, and the light emitting efficiency and continuous driving of a light emitting device are improved.
As other examples of a condensed hydrocarbon having a fluoranthene skeleton in its molecule, as typified by PTL 1, for example, the compounds disclosed in PLTS 2 and 3 are exemplified. Although most of these compounds are improved to have high light emitting efficiency and high stability due to their possession of the electron trapping function, they cannot sufficiently satisfy the color purity required for blue color light emitting materials. Accordingly, further improvements are desired to provide a material satisfying the requirements.